Molded lenses, such as cast molded contact lenses, for example, hydrogel contact lenses, are produced in cast molding assemblies. Molding assemblies can be understood to be lens molds formed from two mold sections or mold halves. One of the mold sections of the molding assembly has a concave surface that defines an anterior surface of a lens. The other mold section of the molding assembly has a convex surface that defines a posterior surface of the lens. To produce lenses, such as contact lenses, it is necessary to separate the two mold sections (e.g., demold the lens mold), and to release the lens product produced in the molding assembly (e.g., delens the lens product) from one of the mold sections.
Delensing a lens product, for example, a contact lens product, from a mold section may involve placing the mold section, for example, the single mold section to which the lens product is held, on a mandrel. This allows the delensing process, that is the releasing of the lens product from the mold section, to be carried out more effectively, for example, relative to not using a mandrel during the delensing. Once the lens product is released or removed from the single mold section, the mold section is removed from the mandrel and a different mold section with a different lens product is placed on the mandrel and the delensing process is repeated.
The above delensing process can be repeated many times, for example, using different mold sections which are structured substantially exactly the same. That is to say, the mold sections may be structured exactly the same, for example, have exactly the same dimensions and configurations and have surfaces which engage the mandrel, i.e., mandrel engagement surfaces, that are exactly the same.
One issue that arises is that the same delensing system or apparatus is often used to remove lens products from differently structured mold sections, such as mold sections having different dimensions or having different configurations or having different mandrel engagement surfaces or any combination thereof. Because, in order to be effective, the mandrel needs to fixedly retain the mold section during at least a portion of the delensing process, the practice has been to replace the mandrel on the delensing system or apparatus every time a differently structured or differently dimensioned mold section or a mold section having a different mandrel engagement surface needed to be delensed. This mandrel replacement step requires a significant amount of downtime of the delensing system or apparatus. Also, the number of mandrels that need to be available is directly related to the number of different mold sections that need to be processed. The downtime for mandrel replacement and the need for different mandrels add to the cost of manufacturing lenses, for example, contact lenses.
Additionally, even when mold sections having mandrel engagement surfaces having the same dimensions and configurations are used, the tolerances of the dimensions and configurations of the mandrel engagement surfaces must be sufficiently tight to ensure that the mandrel engagement surfaces will engage correctly with a standard mandrel. This requires that both the back surface and the front (molding) surface of an individual mold section be formed within tight tolerances, such that expensive mold tooling be used to form both the front and back surfaces of a mold section, and that mold sections having mandrel engagement surfaces which are not within tolerance, for example, are out of specification, be scrapped. Both using expensive mold tooling and having to scrap mold sections which are not within tolerance increase the cost of lens manufacturing.
There are needs for new methods and apparatus useful to address these and other issues involving the manufacture of lenses, such as contact lenses.